Ergonomic evaluation of ergonomically designed chalkboard erasers on shoulder and hand-arm muscle activity among college professors

Teaching professionals regularly use the chalk board eraser or duster throughout their life which leads to several unnoticed musculoskeletal disorders. The purpose of this study was to provide an alternate design for the existing Indian model chalk board eraser, because current eraser design causes noticeable amount of biomechanical load on the wrist, hand and shoulder region when its frequency of usage was high and repetitive. Initially, pilot study was conducted through an online modified Nordic questionnaire among 60 college professors to identify the risky regions of the body due to the use of existing chalk board eraser. This was followed by an experimental trial using surface Electromyography Sensors (sEMG) in which the muscle behaviour was evaluated during the chalkboard erasing process employing three newly designed dusters and a traditional duster. The results revealed that Model A designed with a large palm rest to align the palm and the forearm had better usability and the musculoskeletal distress was reduced when compared with the traditional duster. Whereas Model C designed with slip guards to improve the gripping forces was found to have better performance rating after Model A. Model B provided with separate handle was found to be the worst performer when compared with the conventional duster. Results suggested that providing an improved palm rest and slip guards such as grooves reduces the musculoskeletal distress.